MAN page from Trustix binutils-


Section: User Commands (1)
Updated: January 29, 1993


gprof - display call graph profile data 


gprof [ -abcsz ] [ -e|-Ename] [ -f|-F name] [ -kfromname toname] [ objfile[ gmon.out] ]  


gprofproduces an execution profile of C, Pascal, or Fortran77 programs.The effect of called routines is incorporated in the profile of each caller.The profile data is taken from the call graph profile file(`gmon.out' default) which is created by programsthat are compiled with the-pgoption ofcc(1),pc(1),andf77(1).The-pgoption also links in versions of the library routinesthat are compiled for profiling.Gprofreads the given object file (the default is `a.out')and establishes the relation between its symbol tableand the call graph profile from `gmon.out'.If more than one profile file is specified,thegprofoutput shows the sum of the profile information in the given profile files.

Gprofcalculates the amount of time spent in each routine.Next, these times are propagated along the edges of the call graph.Cycles are discovered, and calls into a cycle are made to share the timeof the cycle.The first listing shows the functionssorted according to the time they representincluding the time of their call graph descendants.Below each function entry is shown its (direct) call graph children,and how their times are propagated to this function.A similar display above the function shows how this function's time and thetime of its descendants is propagated to its (direct) call graph parents.

Cycles are also shown, with an entry for the cycle as a whole anda listing of the members of the cycle and their contributions to thetime and call counts of the cycle.

Second, a flat profile is given,similar to that provided byprof(1).This listing gives the total execution times, the call counts,the time in milliseconds the call spent in the routine itself, andthe time in milliseconds the call spent in the routine itself includingits descendants.

Finally, an index of the function names is provided. 


The following options are available:
suppresses the printing of statically declared functions.If this option is given, all relevant information about the static function(e.g., time samples, calls to other functions, calls from other functions)belongs to the function loaded just before the static function in the`objfile' file.
suppresses the printing of a description of each field in the profile.
the static call graph of the program is discovered by a heuristicthat examines the text space of the object file.Static-only parents or children are shownwith call counts of 0.
-e name
suppresses the printing of the graph profile entry for routinenameand all its descendants(unless they have other ancestors that aren't suppressed).More than one-eoption may be given.Only onenamemay be given with each-eoption.
-E name
suppresses the printing of the graph profile entry for routinename(and its descendants) as-e ,above, and also excludes the time spent inname(and its descendants) from the total and percentage time computations.(For example,-E mcount-E mcleanupis the default.)
-f name
prints the graph profile entry of only the specified routinenameand its descendants.More than one-foption may be given.Only onenamemay be given with each-foption.
-F name
prints the graph profile entry of only the routinenameand its descendants (as-f ,above) and also uses only the times of the printed routinesin total time and percentage computations.More than one-Foption may be given.Only onenamemay be given with each-Foption.The-Foptionoverridesthe-Eoption.
-k fromname toname
will delete any arcs from routinefromnameto routinetoname.This can be used to break undesired cycles.More than one-koption may be given.Only one pair of routine names may be given with each-koption.
a profile file `gmon.sum' is produced that representsthe sum of the profile information in all the specified profile files.This summary profile file may be given to laterexecutions of gprof (probably also with a-s)to accumulate profile data across several runs of an `objfile' file.
prints the version number for gprof, and then exits.
displays routines that have zero usage (as shown by call countsand accumulated time).This is useful with the-coption for discovering which routines were never called.



a.out    the namelist and text space.

gmon.outdynamic call graph and profile.

gmon.sum summarized dynamic call graph and profile. 



``An Execution Profiler for Modular Programs'',by S. Graham, P. Kessler, M. McKusick;Software - Practice and Experience,Vol. 13, pp. 671-685, 1983.

``gprof: A Call Graph Execution Profiler'',by S. Graham, P. Kessler, M. McKusick;Proceedings of the SIGPLAN '82 Symposium on Compiler Construction,SIGPLAN Notices, Vol. 17, No 6, pp. 120-126, June 1982. 


Gprofappeared in 4.2 BSD. 


The granularity of the sampling is shown, but remainsstatistical at best.We assume that the time for each execution of a functioncan be expressed by the total time for the function dividedby the number of times the function is called.Thus the time propagated along the call graph arcs to the function'sparents is directly proportional to the number of times thatarc is traversed.

Parents that are not themselves profiled will have the time oftheir profiled children propagated to them, but they will appearto be spontaneously invoked in the call graph listing, and willnot have their time propagated further.Similarly, signal catchers, even though profiled, will appearto be spontaneous (although for more obscure reasons).Any profiled children of signal catchers should have their timespropagated properly, unless the signal catcher was invoked duringthe execution of the profiling routine, in which case all is lost.

The profiled program must callexit(2)or return normally for the profiling information to be savedin the `gmon.out' file.




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